58 The Morality of Nature 



ten and another with seventeen or more, according to 

 environment. Why does not environment produce in a horse 

 or cow such variabiHty in the matter of legs? It is simply 

 because the mechanism of heredity holds the young to the 

 pattern of the ancestry. It is well known that it is because 

 all the form, and all its attributes, size, shape, material and 

 all others are minutely regulated, controlled and governed 

 by a heredity principle which is marvellously exact. And 

 although we are generally more interested in the vagaries of 

 heredity, that is to say in the transmission of unusual things, 

 it is really in the common repetition of forms and patterns 

 in the constancy of a usual type, that heredity is so 

 wonderful. 



Heredity enables a creature to produce offspring patterned 

 after itself, and its recent ancestors, with constancy of type 

 and without loss of any valuable and settled acquisition, 

 and yet enables it to abandon slowly anything which by 

 long disuse has proven certainly useless. 



The qualities and abilities acquired under the stimulus of 

 environment are thus secured to the race by the principles 

 of heredity. In humanity and in most of the animal species 

 these effects are distributed and equalized among all the 

 individuals of a species by the action of sexual propagation. 

 Without this a difference or improvement acquired by the 

 variation of one individual would remain in the offspring 

 of that individual and would not affect the offspring of any 

 other. But by the dual origin of character in sex every 

 such variation must be shared in the next generation with 

 some other individual and the two heredities combined, and 

 these again with others so that in ten generations over five 



